In the processing and packaging of semiconductor devices, wire bonding continues to be the primary method of providing electrical interconnection between two locations within a package (e.g., between a die pad of a semiconductor die and a lead of a leadframe). More specifically, using a wire bonder (also known as a wire bonding machine) wire loops are formed between respective locations to be electrically interconnected.
An exemplary conventional wire bonding sequence includes: (1) forming a free air ball on an end of a wire extending from a bonding tool; (2) forming a first bond on a die pad of a semiconductor die using the free air ball; (3) extending a length of wire in a desired shape between the die pad and a lead of a leadframe; (4) stitch bonding the wire to the lead of the leadframe; and (5) severing the wire.
When extending a length of wire between a first bonding location (e.g., a die pad) and a second bonding location (e.g., a lead of a leadframe), a series of motions of a bonding tool which carries the wire are performed, where the motions are intended to provide a wire loop having a desired shape, length, etc. Included in the series of motions of the bonding tool are typically certain “arc” motions. Maintaining a proper arc between two points during loop formation is desirable, and if the arc is not properly maintained a number of problems can result including wire leaning, wire buckling, and uncontrollable location of a bend in the wire. Thus, maintaining a proper arc between two points during loop formation is desirable.
Conventional arc motions are provided to a wire bonding machine in the form of data from predefined look up tables or the like. Such predefined data may also take the form of a few predefined (i.e., fixed) time based position functions. Regardless of the actual form of the conventional methods of providing an arc motion (e.g., a look up table, a predefined function, etc.), certain deficiencies may arise. For example, a user who wants to form an arc in a wire loop selects one of the predefined look up tables that may be the closest approximation to the desired arc motion. Unfortunately, even though the closest approximation is selected, a selected predefined look up table may not provide the desired trajectory for many arc motions or the selected predefined look up table may not provide enough control over the trajectory. Thus, one or more of the aforementioned problems (e.g., wire leaning, wire buckling, uncontrollable location of a bend in the wire, amongst others) may result.
Thus, it would be desirable to provide improved methods of determining the trajectory of arc motions of a wire used in the formation of a wire loop, and related wire bonding methods.